Combustion apparatus



June 12, 1934.

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WITNESSE S A. DONALD COMBUSTION APPARATUS Filed Oct. 16, 1931 2Sheets-Sheet l [N VENTOR firecmsnw DONALD.

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ATTORNEY A. DONALD COMBUSTION APPARATUS Filed Oct.

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all a: M A TTORNEY Patented June 12, 1934 PATENT OFFICE COMBUSTIONAPPARATUS Archibald Donald, Moon-es, Pa'., assignor to West? inghouseElectric & Manufacturing Company,- a corporation of PennsylvaniaApplication October 16, 1931, Serial No. 569,343

7 Claims. (01. 110-44) My invention relates to combustion apparatus andmore particularly to underfeed stokers, and it has for a broad object toprovide apparatus of this character which is of improved constructionand arrangement and which is highly flexible and efiicient in operation.

Most underfeed stokers, heretofore known to me, comprise an elongatedretort or retorts and a grate or tuyere structure disposed at the upperlateral edges of the retort. The fuel bed lies over the retorts andtuyeres with the incandescent portions thereof at the top and over thetuyeres. The green coal is fed upwardly from the retorts into theincandescent portions of the fuel bed. The tuyeres, in addition tosupporting portions of the fuel bed, furnish the air necessary forcombustion.

As the coal nears the incandescent portions it becomes heated and as a,result, the volatile gases present in the coal are liberated and theypass upwardly through the fuel bed and combine with the air flowingthrough the tuyeres in regions over the fuel bed to effect combustionthereof. The remaining solid combustible or coke passes onto the tuyeresand there combines with air to complete combustion.

If the fuel bed on an underfeed Stoker exceeds a certain thicknesssufficient air cannot pass through to eifect efficient combustion.Furthermore, if the bed becomes too thin the stoker parts become exposedand are very likely to burn out. It is, therefore, apparent that themechanism for feeding the coal should be so designed and should operatein such a manner as to distribute the coal so as to keep the stokerstructure covered and at the same time not feed too much coal to anyparticular region such as would result in a too thick fuel bed andinefiicient combustion in that region.

Primary feeding mechanism located exteriorly of the furnace is usuallyprovided for forcing the coal into the ,ends of the retorts. Secondaryrams reciprocating along the bottom of the retort are usually providedfor feeding the coal alongthe bottom of the retort and at the same timeupwardly into the fuel bed.

For some time, it has been appreciated by stoker manufacturers that ifthe secondary rams reciprocate at acute angles to the plane of the fuelbed the coal will be fed both longitudinally of the retort and at thesame time upwardly into the active portions of the fuel bed. Practicallyall underfeed' stokers heretofore known to me, are constructed with thesecondary rams -reciprocating at certain angles selected by theirproponents as the proper angle to feed the coal.

However, considerable difiiculty has been experienced by themanufacturers, due to the fact that their stokers do not operateproperly on all coals. Practically any one of the prior structures willoperate properly on coals of a particular character, but difficulty inproperly distributing the coals is experienced when operating with othertypes of coals.

From observation and experiment, I have found that the volatile contentof the coal is the principal factor governing its feedingcharacteristics. I have also found that the size of the angles betweenthe plane of the tuyere structure and the directions of reciprocation ofthe secondary rams have a definite bearing on the manner of feeding thecoal. If the angle is relatively large, the ram produces more of alifting effect and if the angle is relatively small it produces more ofa pushing effect in the longitudinal direction of the retort.

I have also found that if the secondary rams of a stoker are arranged tooperate at relatively small angles a coal having a relatively lowvolatile content can be properly fed, but considerable difficulty isexperienced when a high volatile coal is so fed, this difficulty beingthat the tuyeres cannot be kept properly covered. Also, if the secondaryrams of a stoker are arranged to operate at relatively large angles,satisfactory results are produced with a high volatile coal, but it isdifficult 35 to feed properly a low volatile coal as the fuel bedbecomes too thick and inefficient combustion results. These resultsfollow because of variation in the residual mass after volatilization.With a high volatile coal, there is less mass left after volatilization;and, if 'the secondary rams operate at a relatively large angle, more ofa lifting effect is exerted thereby and the tuyeres are kept properlycovered. Onthe contrary, with a low volatile coal and with more residualsolids left 9s after volatilization, less lifting effect is required tokeep the tuyeres properly covered and, there fore, the rams shouldoperate at a relatively small angle. It is, therefore, a further andmore specific object of this invention to produce a stoker which iscapable of being operated properly with all kinds of coal, and, at thesame time, is no more expensive to manufacture than the previous designsof stokers. M

A further object is to provide a simple and effective means forangularly adjusting the secondary rams so as to produce the properfeeding action for any kind of coal.

These and other objects are effected by my 110 invention as will beapparent from the following description and claims taken in connectionwith the accompanying drawings forming a part of this application inwhich:

Fig. 1 is a longitudinal vertical sectional View of my invention asapplied to the downwardlyinclined multiple-retort type of underfeedstoker;

Fig. 2 is an enlarged fragmentary view of a portion of the structureshown in Fig. 1; and,

Fig. 3 is an enlarged fragmentary sectional view taken on the lineIII-III of Fig. 2.

According to a preferred embodiment of my invention, I provide a stokerincluding a retort, a tuyere structure disposed at the upper lateraledges of the retort, a primary feeding mechanism for forcing green coalinto one end of the retort, at least one secondary ram disposed at thebottom of the retort and reciprocating at an acute angle to the plane ofthe tuyere structure, and means providing for angular adjustment of thesecondary ram so as to vary the size of the angle between the directionof reciprocation and the plane of the tuyere structure and thereby varyits feeding characteristics.

By reason of this structure, if it is desired to feed a coal having arelatively high volatile content the secondary ram may be adjusted toreciprocate at a relatively large angle to the tuyeres; and, if it isdesired to use a low volatile coal, the ram may be changed toreciprocate at a smaller angle. Thus, I have devised a structure whichcan readily and easily be changed so as to feed properly any coal.

Referring now in detail to the structure illustrated in the accompanyingdrawings, it is to be observed that I have shown my invention as appliedto an underfeed stoker of the downwardlyinclined multiple-retort type.The stoker is indicated in its entirety by the reference numeral 1 andit comprises a plurality of parallel spaced retorts 10 androws ofoverlapping tuyere blocks 11 disposed between and supported by the upperedges of the retorts.

A primary ram 12 reciprocating within a ram box 13 serves to feed greencoal from a hopper 14 into the upper end of each of the retorts. Aplurality of reciprocating secondary rams 15, 16, and 17 are arrangedwithin the bottom of each retort, and serve to advance the coal alongthe retort, and at the same time force the coal upwardly and onto thetuyeres. The rams 15, 16, and 17 are driven from a rod 18, the latterhaving a variable lost motion connection 19, with the primary ram.

Air for combustion is supplied to the space beneath the tuyeres from awind box 20. The air flows through the tuyere blocks and combines withthe combustible in the coal to produce combustion in a manner wellunderstood by those skilled in the art.

Each retort comprises a pair of spaced parallel supporting angle irons21 and a pair of side walls 22 supported and secured to the upright legsof the angle irons. The secondary rams 15, 16, and 17 are disposedbetween the side walls 22 and are slidably supported by guide platesalso disposed between the side walls; the ram 15 being supported at itsforward and rearward ends respectively, by guide plates 23 and 24, theram 16 being supported in a like manner by guide plates 25 and 26, andthe ram 17 by guide plates 27 and 28.

As will be observed, the secondary rams reciprocate in directions whichare at acute angles to the general plane of the tuyere rows. As beforestated, the reason for this is to provide both the lifting eifect to thecoal and the pushing effect in the direction of extent of the retort.

Each of the guide plates 23, 24, 25, 26, 2'7, and 28 is pivotallysupported at the sides thereof by bearings 29 which are in turn boltedto the lateral web of a supporting angle iron 21. (See Figs. 2 and 3).Each guide is also supported by a pair of bolts 30 which arelongitudinally spaced from the bearing blocks 29. The bolts 30 arehinged at their upper ends to their respective guide plates and aresecured at their lower ends by nuts 31 and 32 to the lateral web of thesupporting angle iron. The lower ends of the bolts 30 extend throughopenings in the Web and the nuts 31 and 32 are screwed to the bolt 30 atopposite sides of the Web and thereby serve to firmly secure the boltand web. The angular position of each guide plate may be readily changedby a simple manipulation of the nuts 31 and 32. Obviously, as the guideplates support the secondary rams, angular adjustment of the guideplates results in an angular adjustment of the secondary ram supportedthereby.

It is to be observed that the guide plates 23 and 25 are divided midwaytheir length into two pieces, the forward pieces being firmly secured bythe bearing blocks 29 and bolts 30 and the rearward piece being hingedto the forward piece and resting at its rear end on the top surface ofthe secondary ram. The reason for this construction is to preventclearance between the top of the ram and the guide plate and therebyprevent sifting of the coal into the air chamber. The hinged rear endsperform this function irrespective of the angular position of theforward ends.

While I have shown my invention in but one form, it will be obvious tothose skilled in the art that it is not so limited but is susceptible ofvarious changes and modifications without departing from the spiritthereof, and I desire, therefore, that only such limitations shall beplaced thereupon as are imposed by the prior art or as are specificallyset forth in the appended claims.

What I claim is:

1. In underfeed stoker apparatus, the combination of an elongated troughor retort; air emitting grate structure at the upper lateral edges ofthe retort; primary feeding means for forcing solid fuel into one end ofthe retort; secondary feeding means reciprocating within the retort andat an angle to the longitudinal center line of the retort so as to forcethe fuel both longitudinally of the retort and upwardly onto 'the gratestructure; and means for varying the angle with respect to said centerline at which the secondary feeding mechanism re iprocates so as to varythe fuel feeding characteristics thereof.

2. In underfeed stoker apparatus, the combination of an elongated troughor retort; air emitting grate structure at the upper lateral edges ofthe retort; primary feeding means for forcing solid'fuel into one end ofthe retort; at least one secondary ram disposed Within the retort;supporting means for the secondary ram and providing for reciprocatorymovement of said ram in a direction which is at an angle to thelongitudinal center line of the retort so as to force the fuel bothlongitudinally of the retort and also upwardly over the sides thereof;and means I nation of an elongated trough or retort; air emitting gratestructure at the upper lateral edges of the retort; primary feedingmeans for forcing solid fuel into one end of the retort; a plurality ofsecondary rams disposed within the retort; guiding and supporting meansfor the rams and providing for reciprocatory movement thereof indirections which are at angles to the longitudinal center line of theretort so as to force the fuel both longitudinally of the retort andupwardly over the sides thereof and onto the grate structure; andadjusting means for the guiding and supporting means whereby the anglewith respect to said center line at which each ram reciprocates may bevaried so as tochange the fuel feeding characteristics thereof.

4. In underfeed stoker apparatus, the combination with alternatelyarranged retorts and rows of tuyeres inclined downwardly from the fuelreceiving end and primary feeding mechanism for forcing solid fuel intothe fuel receiving end of the retorts; of reciprocatory secondaryfeeding mechanism disposed within each of the retorts and operating atacute angles with respect to the longitudinal center lines of theirrespective retorts for feeding the fuel both longitudinally of theretorts and upwardly and out onto the tuyere rows; and means providingfor varying the angles with respect to said center lines at which thesecondary feeding mechanisms operate so as to change the fuel feedingcharacteristics thereof to suit different fuels.

5. In underfeed stoker apparatus, the combination with alternatelyarranged retorts and rows of tuyeres inclined downwardly from the fuelreceiving end and primary feeding mechanism for forcing solid fuel intothe fuel receiving end of the retorts; of at least one secondary ramdisposed within each of the retorts; means for supporting each of therams so as to provide for reciprocatory movement thereof at an acuteangle to the longitudinal center line of its respective retort; andmeans for adjusting the supporting means so as to vary the acute anglewith respect to said center line of the retort at which the ramreciprocates.

6. In underfeed stoker apparatus, the combination with alternatelyarranged retorts and rows of tuyeres inclined downwardly from the fuelreceiving end and primary feeding mechanism for forcing solid fuel intothe fuel receiving end of the retorts; of a plurality of secondary ramsdisposed within each of'the retorts; supporting means for each of therams and providing for reciprocatory movement of the latter at acuteangles to the longitudinal center line of their respective retorts; andmeans for adjusting the supporting means so as to vary the acute anglesat which the rams reciprocate.

7. In underfeed stoker apparatus, the combination with alternatelyarranged retorts and rows of tuyeres inclined downwardly from the fuelreceiving end and primary feeding mechanism 100 for forcing solid fuelinto the fuel receiving end of the retorts; of a plurality of secondaryrams disposed within each of the retorts; supporting means for each ofthe rams and providing for reciprocatory movement of the latter at acute105 angles to the longitudinal center lines of their respective retorts;and means providing for the adjustment of the supporting means for eachof the rams so as to vary the acute angle of reciprocation of each ofthe rams with respect to the 110 others.

ARCHIBALD DONALD.

